I'm not quite familiar with organic shapes yet so the main goal of this exercise was to learn and play around with the shapes and the way it flows in a short period of time (few hours from creation to rendering) and not to really end with photorealistic final render.
I based it on photos references and concepts but I also looked at the Rocks creation process of Daniel Thiger that is for me a really strong reference regarding rocks materials.
I learned a lot doing this exercise and I'll definitely continue to progress on rocks creation!